EP0982598B1 - Magnetresonanzsystem mit Shim-Ringen - Google Patents

Magnetresonanzsystem mit Shim-Ringen Download PDF

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Publication number
EP0982598B1
EP0982598B1 EP99306173A EP99306173A EP0982598B1 EP 0982598 B1 EP0982598 B1 EP 0982598B1 EP 99306173 A EP99306173 A EP 99306173A EP 99306173 A EP99306173 A EP 99306173A EP 0982598 B1 EP0982598 B1 EP 0982598B1
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EP
European Patent Office
Prior art keywords
rings
magnetic
imaging volume
ferrous
magnetic resonance
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Lifetime
Application number
EP99306173A
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English (en)
French (fr)
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EP0982598A3 (de
EP0982598A2 (de
Inventor
John V. M. Mcginley
Ian R. Young
Gordon D. Demeester
Ilmari Kinanen
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Koninklijke Philips NV
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Koninklijke Philips Electronics NV
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Publication of EP0982598A3 publication Critical patent/EP0982598A3/de
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    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
    • G01R33/00—Arrangements or instruments for measuring magnetic variables
    • G01R33/20—Arrangements or instruments for measuring magnetic variables involving magnetic resonance
    • G01R33/28—Details of apparatus provided for in groups G01R33/44 - G01R33/64
    • G01R33/38—Systems for generation, homogenisation or stabilisation of the main or gradient magnetic field
    • G01R33/383—Systems for generation, homogenisation or stabilisation of the main or gradient magnetic field using permanent magnets
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
    • G01R33/00—Arrangements or instruments for measuring magnetic variables
    • G01R33/20—Arrangements or instruments for measuring magnetic variables involving magnetic resonance
    • G01R33/28—Details of apparatus provided for in groups G01R33/44 - G01R33/64
    • G01R33/38—Systems for generation, homogenisation or stabilisation of the main or gradient magnetic field
    • G01R33/387—Compensation of inhomogeneities
    • G01R33/3873—Compensation of inhomogeneities using ferromagnetic bodies ; Passive shimming

Definitions

  • Open magnets typically include a ferrous flux return path in the form of a "C", "H", or four-poster arrangement.
  • the flux return paths have an open gap within which the patient is disposed for imaging. Due to the difference in the susceptibility of the flux return path and the air in the patient gap, there tends to be non-linearity and other magnetic flux errors in the patient receiving gap.
  • a large ferrous pole piece is typically positioned at the ends of the flux return path on either side of the patient receiving gap.
  • the pole pieces are shaped and contoured, as appropriate, to generate a more uniform magnetic flux between the pole pieces.
  • a heavy ferrous ring known as a Rose ring, is positioned along the circumference of the pole piece to drive the magnetic flux towards the centre of the pole piece and the patient receiving gap.
  • annular primary magnet coils 10 which preferably are superconducting, are disposed in a pair of parallel, horizontal planes on either side of an imaging volume 12 .
  • the primary magnet coils generate a temporally constant magnetic field through the imaging volume, in the vertical direction in the illustrated embodiment.
  • a magnetic flux return path includes an annular ferrous ring 14 , a top plate 16 , a plurality of posts 18 , a bottom plate 20 , a lower annular ferrous ring 22 , and a ferrous plug 24 .
  • the flux return path provides a low resistance flux path in a loop or series of loops with a gap across the imaging volume 12 .
  • a single magnet may be utilized or the magnet(s) may be placed at other locations along the flux.
  • the MRI magnet described above has high homogeneity, good patient access and low forces on the driver coils.
  • One advantage is that it facilitates the design of open magnets with stronger magnetic fields.
  • Another advantage is that it improves magnetic field homogeneity.
  • Another advantage resides in improved patient access.
  • Another advantage resides in a reduction of potential eddy currents.
  • Yet another advantage resides in the reduced pole mass.

Landscapes

  • Physics & Mathematics (AREA)
  • Condensed Matter Physics & Semiconductors (AREA)
  • General Physics & Mathematics (AREA)
  • Magnetic Resonance Imaging Apparatus (AREA)

Claims (8)

  1. Magnetresonanzsystem mit einem Paar Eisenringen (26), die parallel zueinander auf gegenüberliegenden Seiten eines Bildgebungsvolumens (12) angeordnet sind, einem magnetischen Rückflusspfad, der von einem der Ringe (26) entfernt um das Bildgebungsvolumen (12) herum zu dem anderen Ring (26) verläuft, einer Magnetflussquelle, die einen Magnetfluss durch das Bildgebungsvolumen (12) zwischen den Ringen (26) und durch den magnetischen Rückflusspfad bewirkt, und das weiterhin Folgendes umfasst: einen Shim-Satz hoher Ordnung (30) mit einer Vielzahl von einzelnen magnetisierten Ringen (32a-d) umgeben von mindestens einem der Eisenringe (26), um den das Bildgebungsvolumen (12) durchquerenden Magnetfluss zu fokussieren und den Fluss gleichmäßiger zu machen, dadurch gekennzeichnet, dass eine nicht-magnetische Nichteisen-Haltestruktur (34) vorgesehen ist, um die magnetisierten Ringe (32a-d) zu tragen, und Gradientenspulen (50) auf einer dem Bildgebungsvolumen (12) gegenüberliegenden Seite der magnetisierten Ringe (32a-d) angeordnet sind.
  2. Magnetresonanzsystem nach Anspruch 1, wobei die magnetisierten Ringe (32a-d) in konzentrischen Kreisen angeordnet sind.
  3. Magnetresonanzsystem nach Anspruch 1 oder Anspruch 2, wobei mindestens einer der Shim-Satz-Ringe hoher Ordnung (32a-32d) eine zu einem anderen der magnetisierten Ringe entgegengesetzte magnetische Polarität aufweist.
  4. Magnetresonanzsystem nach einem der Ansprüche 1 bis 3, wobei die Magnetflussquelle mindestens einen ringförmigen Magneten (10) umfasst, der um einen der Eisenringe (26) herum und angrenzend an den Rückflusspfad angeordnet ist.
  5. Magnetresonanzsystem nach einem der Ansprüche 1 bis 4, wobei mindestens einer der magnetisierten Ringe (32a-32d) aus dauermagnetischem Material konstruiert ist.
  6. Magnetresonanzverfahren, das Folgendes umfasst:
    - Induzieren eines Magnetflusses, der durch ein Bildgebungsvolumen eines Magnetresonanzsystems fließt, das ein Paar Eisenringe (26) umfasst, welche parallel zueinander an gegenüberliegenden Seiten des genannten Bildgebungsvolumens (12) angeordnet sind, wobei ein magnetischer Rückflusspfad vorgesehen ist, der entfernt um das Bildgebungsvolumen (12) herum verläuft.
    - Anpassen der Homogenität des Magnetflusses mit einem Shim-Satz (30), der eine Vielzahl einzelner magnetisierter Ringe (32a-32d) auf einer nicht-magnetischen Nichteisen-Haltestruktur umfasst, wobei die genannten Ringe von mindestens einem der Eisenringe (26) umgeben sind, und
    - Induzieren von Magnetfeldgradienten von einer Seite des Bildgebungsvolumens (12) zur anderen durch Gradientenspulen (50), die auf einer dem Bildgebungsvolumen (12) gegenüberliegenden Seite der magnetisierten Ringe (32a-d) angeordnet sind.
  7. Verfahren nach Anspruch 6, wobei das Eisenelement (26) ein ringförmiger Ring aus Kobaltstahl ist und das dauermagnetische Material ringförmige Ringe (32a-32d) aus NdBFe-Legierung umfasst.
  8. Verfahren nach Anspruch 6 oder Anspruch 7, das Folgendes umfasst: Zuführen von Hochfrequenzimpulsen, um Magnetresonanz anzuregen; Empfangen von angeregten Resonanzsignalen aus dem Bildgebungsvolumen; Rekonstruieren der empfangenen Resonanzsignale zu einer Bilddarstellung.
EP99306173A 1998-08-28 1999-08-03 Magnetresonanzsystem mit Shim-Ringen Expired - Lifetime EP0982598B1 (de)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
US141708 1998-08-28
US09/141,708 US6218838B1 (en) 1998-08-28 1998-08-28 MRI magnet with high homogeneity, patient access, and low forces on the driver coils

Publications (3)

Publication Number Publication Date
EP0982598A2 EP0982598A2 (de) 2000-03-01
EP0982598A3 EP0982598A3 (de) 2002-02-13
EP0982598B1 true EP0982598B1 (de) 2007-07-11

Family

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Family Applications (1)

Application Number Title Priority Date Filing Date
EP99306173A Expired - Lifetime EP0982598B1 (de) 1998-08-28 1999-08-03 Magnetresonanzsystem mit Shim-Ringen

Country Status (4)

Country Link
US (1) US6218838B1 (de)
EP (1) EP0982598B1 (de)
JP (1) JP2000070238A (de)
DE (1) DE69936494T2 (de)

Cited By (1)

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CN107533119A (zh) * 2015-04-10 2018-01-02 圣纳普医疗(巴巴多斯)公司 用于磁共振成像的匀场线圈

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US6157278A (en) * 1997-07-23 2000-12-05 Odin Technologies Ltd. Hybrid magnetic apparatus for use in medical applications
JP2001078982A (ja) * 1999-09-16 2001-03-27 Hitachi Medical Corp 開放型磁石装置
US6335670B1 (en) * 2000-04-14 2002-01-01 Marconi Medical Systems Finland, Inc. Mri system with split rose ring with high homogeneity
US6861933B1 (en) 2001-05-17 2005-03-01 Mitsubishi Denki Kabushiki Kaisha Superconductive magnet device
EP1260827B1 (de) * 2001-05-17 2008-12-31 Mitsubishi Denki Kabushiki Kaisha Supraleitender Magnet für die bildgebende magnetische Resonanz
JP3694659B2 (ja) 2001-07-16 2005-09-14 株式会社日立製作所 マグネット及びその磁場調整方法並びに磁気共鳴撮像装置
US6627003B2 (en) 2001-10-24 2003-09-30 Ge Medical Systems Global Technology Company, Llc NMR shim forming method
AU2002351020A1 (en) * 2001-12-10 2003-06-23 Koninklijke Philips Electronics N.V. Open magnetic resonance imaging (mri) magnet system
DE10161925B4 (de) * 2001-12-17 2005-08-18 Siemens Ag Verfahren zum Aufnehmen von Magnetresonanzsignalen eines Objekts mittels einer Magnetresonanzanlage und Rekonstruieren eines Bildes anhand der aufgenommenen Magnetresonanzsignale, sowie Computerprogrammprodukt und Magnetresonanzanlage
US7215231B1 (en) 2002-08-16 2007-05-08 Fonar Corporation MRI system
US7242191B2 (en) * 2002-11-25 2007-07-10 General Electric Company Cold mass support structure and helium vessel of actively shielded high field open MRI magnets
CN100504432C (zh) * 2003-05-23 2009-06-24 西门子（中国）有限公司 磁共振设备中的静磁场调节方法及其静磁场发生装置
DE102004003535B3 (de) * 2004-01-23 2005-10-13 Siemens Ag Erzeuger eines zeitvariablen Magnetfelds eines Magnetresonanzgeräts und Magnetresonanzgerät mit einem derartigen Erzeuger eines zeitvariablen Magnetfelds
ATE420375T1 (de) 2004-06-17 2009-01-15 Koninkl Philips Electronics Nv Magnetresonanzabbildungssystem mit eisenunterstütztem magnetfeldgradientensystem
JP4749699B2 (ja) * 2004-11-17 2011-08-17 株式会社日立メディコ 磁気共鳴イメージング装置
EP2511724B1 (de) 2008-06-24 2019-03-13 Alberta Health Services Verfahren zur Bestimmung eines Magnetfeldes für ein Bildgebungsvolumen
CN102360691B (zh) * 2011-06-24 2013-03-13 中国科学院电工研究所 一种带有铁环结构的开放式核磁共振磁体系统
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Cited By (2)

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Publication number Priority date Publication date Assignee Title
CN107533119A (zh) * 2015-04-10 2018-01-02 圣纳普医疗(巴巴多斯)公司 用于磁共振成像的匀场线圈
CN107533119B (zh) * 2015-04-10 2020-07-28 圣纳普医疗(巴巴多斯)公司 用于磁共振成像的匀场线圈

Also Published As

Publication number Publication date
DE69936494T2 (de) 2008-03-13
EP0982598A3 (de) 2002-02-13
EP0982598A2 (de) 2000-03-01
DE69936494D1 (de) 2007-08-23
US6218838B1 (en) 2001-04-17
JP2000070238A (ja) 2000-03-07

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